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<blockquote data-quote="00PewterSS" data-source="post: 2077149" data-attributes="member: 562040">I also have worked with hydraulic test equipment.&nbsp; The servo-hydraulic systems we use for automotive testing can easily work to 40Hz and probably 100Hz as a subwoofer where there is very little mass to move.&nbsp; I have never considered doing it.&nbsp; When we have run frequency sweeps it excites the bedplates in harmonics, so that sort of act as a subwoofer.Anyway, with the proper controls you could precisely control the movement.&nbsp; With a good controller with limits, you can limit its travel, and limit the force it exerts.&nbsp; To get a specific response what we do is use software where we create a transfer function between the input and output and physically iterate until the input matches the response as best the equipment can.&nbsp; If you assume the transfer function is perfectly linear you don&#039;t need to iterate, but that is unlikely.&nbsp; What signal are you going to try to reproduce?&nbsp; Do you want to input a specific frequency or play music?Your idea will definately work, but electric actuators (like in a speaker) are far quicker and more precise than pneumatic or hydraulic.&nbsp; The only way this project would make sense to do is if it you want some rediculously large excursion, but then I don&#039;t know that you could get that kind of acceleration out of your actuator.Anyway, cool idea!Brian</blockquote>

[QUOTE="00PewterSS, post: 2077149, member: 562040"] I also have worked with hydraulic test equipment. The servo-hydraulic systems we use for automotive testing can easily work to 40Hz and probably 100Hz as a subwoofer where there is very little mass to move. I have never considered doing it. When we have run frequency sweeps it excites the bedplates in harmonics, so that sort of act as a subwoofer. Anyway, with the proper controls you could precisely control the movement. With a good controller with limits, you can limit its travel, and limit the force it exerts. To get a specific response what we do is use software where we create a transfer function between the input and output and physically iterate until the input matches the response as best the equipment can. If you assume the transfer function is perfectly linear you don't need to iterate, but that is unlikely. What signal are you going to try to reproduce? Do you want to input a specific frequency or play music? Your idea will definately work, but electric actuators (like in a speaker) are far quicker and more precise than pneumatic or hydraulic. The only way this project would make sense to do is if it you want some rediculously large excursion, but then I don't know that you could get that kind of acceleration out of your actuator. Anyway, cool idea! Brian [/QUOTE]

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